The invention relates generally to the field of photography, and in particular to attachable flash apparatus useful with one-time-use cameras.
One-time-use cameras are rapidly gaining in popularity due to in large part to their convenience and low cost relative to user-reloadable cameras. Many of such cameras include a built-in flash device to enable indoor picture taking. For cost reasons, such flash devices are typically fixed in place and, because of the small size of the cameras, are necessarily located close to the optical axis of the taking lens. As a result, the phenomenon known as xe2x80x9cred-eyexe2x80x9d becomes a problem. Red-eye occurs when flash light is reflected by a subject""s retina through the taking lens onto the exposed image frame. Numerous techniques are known for reducing the red-eye effect. One of such techniques involves the use of a pop-up flash device that moves the flash emitter away from the optical axis of the taking lens. Such a built-in, pop-up arrangement, while effective, is costly to implement and would not be suitable for one-time-use cameras where cost must be kept at a minimum.
U.S. Pat. No. 5,384,611 discloses a user-reloadable camera with a retractable built-in flash and provision for attachment of an external flash. When the external flash is mounted on the camera, the retractable flash which is close to the optical axis of the taking lens is retracted into the camera and does not fire. Thus, the external flash unit and built-in flash unit do not fire simultaneously. Since the spaced, externally mounted flash is the sole source of flash emission, the red-eye effect is effectively eliminated. However, the disclosed arrangement involves the use of a movable built-in flash unit which requires that, when the external flash is mounted on the camera, the built-in flash be moved to cause the built-in flash to be inactivated, a costly feature for one-time-use cameras. Moreover, the externally mounted flash unit is a self-contained unit that requires the unit have its own flash charging circuit and battery power supply. It is desirable for cost reasons that such components be eliminated from the external flash unit.
In accordance with the invention, therefore, there is provided a one-time-use camera and detachable flash system which comprises a one-time-use camera having a housing, a first mounting structure accessible on an outer surface of the housing, a taking lens, and a built-in flash unit, the built-in flash unit having a charging circuit, a main flash capacitor, a first flash emission device fixedly mounted in the camera, and a flash trigger circuit including a trigger switch, the camera further including externally accessible electrical terminals connected to the main flash capacitor and to the flash trigger circuit. The system further comprises an external flash unit having a second flash emission device and a housing with a second mounting structure thereon configured to mate with the first mounting structure on the camera housing permitting the external flash unit to be detachably mounted on the camera with the second flash emission device spaced farther away from the taking lens than the first flash emission device. The external flash unit is devoid of a charging circuit and battery power supply and further includes an electronically actuated flash trigger circuit, circuit means connected to the electronically actuated flash trigger circuit, and external electrical connection terminals connected to the electronically actuated flash trigger and to the second flash emission device. The electrical connection terminals are positioned on the external flash unit housing such that, when the external flash unit is mounted on the camera, the second flash emission device is connected to the camera flash capacitor and the circuit means is connected to the camera trigger circuit. The circuit means is operative to disable the camera trigger circuit from initiating flash emission by the first flash emission device and is responsive to closure of the trigger switch to send a pulse signal from the camera trigger circuit to the external flash trigger circuit to initiate flash emission by the second flash emission device. By virtue of the farther away spacing of the second flash emission device from the taking lens than the first flash emission device and the disabling of the first flash emission device, red-eye effect from a subject being photographed is substantially eliminated.
These and other aspects, objects, features and advantages of the present invention will be more clearly understood and appreciated from a review of the following detailed description of the preferred embodiments and appended claims, and by reference to the accompanying drawings.